Home Embedded PC based on Thin Mini-ITX. strange symptoms

Question

Do it yourself

I have an embedded system based on the H77TN motherboard from Gigabyte. Everything is exclusively for watching movies and surfing the Internet. Works completely on passive cooling.
One fine evening while watching a movie, the computer turned itself off. At first I thought they turned off the light, but no. A minute before that, I just watched the temperature - 42 C. After 2 minutes, I pulled it out of the socket, opened the case and found strange smudges under the resistors (1mm * 2mm without any designations, but shaped like resistors, only very small). I removed the smudges without much difficulty with a cotton swab, although this liquid was slightly viscous. I plug it in and notice that 2 transistors in the south bridge area heat up to about 80 C in a couple of seconds, and I didn’t even press the power button.
Maybe someone else has come across something similar. I am very interested in the reason for this phenomenon ... In 2 service centers they shrug their shoulders, I have not applied to others yet.